
/* @(#)w_atanh.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
FUNCTION
    <<atanh>>, <<atanhf>>---inverse hyperbolic tangent

INDEX
    atanh
INDEX
    atanhf

ANSI_SYNOPSIS
    #include <math.h>
    double atanh(double <[x]>);
    float atanhf(float <[x]>);

TRAD_SYNOPSIS
    #include <math.h>
    double atanh(<[x]>)
    double <[x]>;

    float atanhf(<[x]>)
    float <[x]>;

DESCRIPTION
    <<atanh>> calculates the inverse hyperbolic tangent of <[x]>.

    <<atanhf>> is identical, other than taking and returning
    <<float>> values.

RETURNS
    <<atanh>> and <<atanhf>> return the calculated value.

    If
    @ifnottex
    |<[x]>|
    @end ifnottex
    @tex
    $|x|$
    @end tex
    is greater than 1, the global <<errno>> is set to <<EDOM>> and
    the result is a NaN.  A <<DOMAIN error>> is reported.

    If
    @ifnottex
    |<[x]>|
    @end ifnottex
    @tex
    $|x|$
    @end tex
    is 1, the global <<errno>> is set to <<EDOM>>; and the result is
    infinity with the same sign as <<x>>.  A <<SING error>> is reported.

    You can modify the error handling for these routines using
    <<matherr>>.

PORTABILITY
    Neither <<atanh>> nor <<atanhf>> are ANSI C.

QUICKREF
    atanh - pure
    atanhf - pure


*/

/*
 * wrapper atanh(x)
 */

#include "fdlibm.h"
#include <errno.h>

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__
    double atanh(double x)      /* wrapper atanh */
#else
    double atanh(x)         /* wrapper atanh */
    double x;
#endif
{
#ifdef _IEEE_LIBM
    return __ieee754_atanh(x);
#else
    double z,y;
    struct exception exc;
    z = __ieee754_atanh(x);
    if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
    y = fabs(x);
    if(y>=1.0) {
        if(y>1.0) {
                /* atanh(|x|>1) */
                exc.type = DOMAIN;
                exc.name = "atanh";
        exc.err = 0;
        exc.arg1 = exc.arg2 = x;
                exc.retval = 0.0/0.0;
                if (_LIB_VERSION == _POSIX_)
                  Djy_SaveLastError(EDOM);
                else if (!matherr(&exc)) {
                  Djy_SaveLastError(EDOM);
                }
        } else {
                /* atanh(|x|=1) */
                exc.type = SING;
                exc.name = "atanh";
        exc.err = 0;
        exc.arg1 = exc.arg2 = x;
        exc.retval = x/0.0; /* sign(x)*inf */
                if (_LIB_VERSION == _POSIX_)
                  Djy_SaveLastError(EDOM);
                else if (!matherr(&exc)) {
                  Djy_SaveLastError(EDOM);
                }
            }
        if (exc.err != 0)
              Djy_SaveLastError(exc.err);
            return exc.retval;
    } else
        return z;
#endif
}

#endif /* defined(_DOUBLE_IS_32BITS) */




